Harnessing Pnictogen and Chalcogen Bonding for Cross-Electrophile C–P ^III Coupling of Chlorophosphines with Thianthrenium Salts

While reductive C-P(III) cross-couplings have proven valuable for the synthesis of triarylphosphines, they often face challenges when applied to triarylphosphines bearing structurally complex aryl groups. Herein, we report an alternative and streamlined reductive C-P(III) cross-coupling strategy, in which aryl sulfonium salts─readily prepared from a wide range of arenes─are directly transformed into triarylphosphines via coupling with chlorophosphines, enabled by pnictogen and chalcogen bonding interactions. Mechanistic investigations further highlight the pivotal role of pnictogen and chalcogen bonding in facilitating the formation of photoactive charge-transfer complexes.